AMERICAN COLEOPTERA. 227 



anterior dilated in the males and fimbriate at the sides. Tliornx truncate in 

 front, sides more or less margined. Elytra with distinct margical line and 

 with an epif)leiiral fold of variable width usually wide, rarely narrow {caro- 

 linus). Metasternum moderately long, body winged. Abdomen of six distinct 

 segments. 



The head exhibits some variation in form within specific limits; 

 that is, while the eyes in some individuals are very close to the hind 

 angle of the head, in others the head is notably prolonged behind 

 them. This is neither sexual nor specific. 



The antennae are always spoken of as ten-jointed but the true 

 second joint appears as a node at the base of. the one usually called 

 the second. There is no variation in the form of joints 3 — 6 worthy 

 of special mention. The club is slightly variable in the degree of 

 the emargination of the second and third joints, so that the first and 

 fourth joints meet when the club is closed in some species in others 

 not. This character does not seem of any further value. 



The clypeus is separated from the front by a fine suture and its 

 anterior portion is membranous and may be orange-red or piceous, 

 this portion is called the rhmarimn and varies in size and shape but 

 not sufficiently for use in the separation of the species. 



The form of the thorax plays an important part in arranging the 

 species in natural groups and requires special mention. 



The first form or that which is most unlike all the others is that of 

 carolinus. Here the thorax is oval not wider than long, narrowed 

 behind, the lateral margin extremely narrow, the disc (for this genus), 

 very convex and without any trace of the anterior sinuous impressed 

 line. The punctuation is also peculiar. This form is called " oboval, 

 not margined." 



The second form is that represented by americanus, orhkoUis and 

 Sayi, in which the thorax is orbicular, truncate in front the sides 

 arcuate and rather broadly margined. These species are moreover 

 peculiar in having the elytra more oval and when we view the species 

 from the side there seems to be a very distinct transverse depression of 

 the elytra behind the base. The last two species above mentioned have 

 erect hairs on the elytra. This form of thorax is called " orbicular." 



The next form of thorax is that of viarffhiatus, obscurus and 

 (juttida, called in the following pages " transversely cordate." The 

 thorax is broader than long, the sides very narrowly maririued and 

 at middle sinuate. The anterior sinuous impression of the thorax 

 is well marked. 



The form in j^ustiilafus, vespilloides and (omentosiis, is called " trans- 



